Electrocatalytic Deep Dehalogenation and Mineralization of Florfenicol: Synergy of Atomic Hydrogen Reduction and Hydroxyl Radical Oxidation over Bifunctional Cathode Catalyst.

It is difficult to achieve deep dehalogenation or mineralization for halogenated antibiotics using traditional reduction or oxidation processes, posing the risk of microbial activity inhibition and bacterial resistance. Herein, an efficient electrocatalytic process coupling atomic hydrogen (H*) reduction with hydroxyl radical (•OH) oxidation on a bifunctional cathode catalyst is developed for the deep dehalogenation and mineralization of florfenicol (FLO). Atomically dispersed NiFe bimetallic catalyst on nitrogen-doped carbon as a bifunctional cathode catalyst can simultaneously generate H* and •OH through H2O/H+ reduction and O2 reduction, respectively. The H* performs nucleophilic hydro-dehalogenation, and the •OH performs electrophilic oxidization of the carbon skeleton. The experimental results and theoretical calculations indicate that reductive dehalogenation and oxidative mineralization processes can promote each other mutually, showing an effect of 1 + 1 > 2. 100% removal, 100% dechlorination, 70.8% defluorination, and 65.1% total organic carbon removal for FLO are achieved within 20 min (C0 = 20 mg·L-1, -0.5 V vs SCE, pH 7). The relative abundance of the FLO resistance gene can be significantly reduced in the subsequent biodegradation system. This study demonstrates that the synergy of reduction dehalogenation and oxidation degradation can achieve the deep removal of refractory halogenated organic contaminants.

Filter-membrane treatment of flowing antibiotic-containing wastewater through peroxydisulfate-coupled photocatalysis to reduce resistance gene and microbial inhibition during biological treatment.

The direct biological treatment of antibiotics containing wastewater brings about a potential risk of antibiotic resistance genes (ARGs) spread. Although advanced oxidation technologies based on photocatalysis generally appear effective at degrading antibiotics in wastewater, the fate of ARGs in succeeding biological treatment system is still unknown. Herein, a filter-membrane-like carbon cloth-immobilized Fe2O3/g-C3N4 photocatalyst is fabricated through immersion-calcination method. Peroxydisulfate-coupled photocatalysis system is developed to degrade tetracycline (TC, an emerging refractory antibiotic pollutant). The system can produce energetic active species (·OH, SO4·-, h+, O2·- and 1O2), exhibiting a superior performance towards TC degradation in static and continuous flow processes under visible-light irradiation. The pretreatment can eliminate the antibacterial activity of antibiotics wastewater, and the chemical oxygen demand removal is greatly enhanced in subsequent anaerobic or aerobic process. The microbial diversity and richness in activated sludge for pretreated water sample are significantly higher than those for the water sample without pretreatment. Meanwhile, the pretreatment can decrease the relative abundance of potential hosts of ARGs and reduce the emergence as well as dissemination risk of ARGs. This study uncovers the effect of pretreatment of antibiotics containing wastewater using advanced oxidation technologies on the treatment efficacy and antibiotic resistome fate in biological treatment system.

Boosting Electrocatalytic Oxygen Evolution: Superhydrophilic/Superaerophobic Hierarchical Nanoneedle/Microflower Arrays of CexCo3-xO4 with Oxygen Vacancies.

The oxygen evolution reaction has become the bottleneck of electrochemical water splitting for its sluggish kinetics. Developing high-efficiency and low-cost non-noble-metal oxide electrocatalysts is crucial but challenging for industrial application. Herein, superhydrophilic/superaerophobic hierarchical nanoneedle/microflower arrays of Ce-substituted Co3O4 (CexCo3-xO4) in situ grown on the nickel foam are successfully constructed. The hierarchical architecture and superhydrophilic/superaerophobic interface can be facilely regulated by controlling the introduction of Ce into Co3O4. The unique feature of hierarchical architecture and superhydrophilic/superaerophobic interface is in favor of electrolyte penetration and bubbles release. In addition, the presence of oxygen vacancy and Ce endows the catalyst with enhanced intrinsic activity. Benefiting from these advantages, the optimized Ce0.12Co2.88O4 catalyst shows a superior electrocatalytic performance for the oxygen evolution reaction (OER) with an overpotential of 282 mV at 20 mA cm-2, and a Tafel slope of 81.4 mV dec-1. The turnover frequency of 0.0279 s-1 for Ce0.12Co2.88O4 is 9.3 times larger than that for Co3O4 at an overpotential of 350 mV. Moreover, the optimized Ce0.12Co2.88O4 catalyst shows a robust long-term stability in alkaline media.

Electrocatalytic deep dehalogenation of florfenicol using Fe-doped CoP nanotubes array for blocking resistance gene expression and microbial inhibition during biochemical treatment.

Resistance gene expression and microbial inhibition by halogenated antibiotics is a major environmental concern. Although electrocatalytic dehalogenation can detoxify halogenated antibiotics, the effect of dehalogenation treatment on resistance gene expression and microbial inhibition is poorly understood. Herein, a novel electrocatalyst of Fe-doped CoP nanotubes array on nickel foam (Fe-CoP NTs/NiF) is prepared through a simple ultrasonication of Fe-doped CoP nanowires hydrothermally grown on NiF. The transformation from nanowires to nanotubes improves the crystallinity of CoP and fully exposes active sites, producing energetic atomic hydrogen for dehalogenation. Fe-CoP NTs/NiF exhibits a superior dehalogenation performance towards refractory florfenicol (FLO), achieving 100% removal within 20 min (‒1.2 V vs Ag/AgCl, C0 = 20 mg L‒1). The dechlorination ratio reaches nearly 100%, and the defluorination ratio achieves 36.8% within 50 min, showing the best electrocatalytic dehalogenation performance reported so far. Microbial community and correlation analysis show that Proteobacteria is the main potential host of FLO resistance gene. Electrocatalytic reductive dehalogenation pretreatment of FLO can reduce microbial inhibition, maintaining microbial richness and diversity in the subsequent biochemical treatment unit. The electrocatalytic reductive dehalogenation treatment can significantly reduce the relative abundance of FLO resistance gene, showing a reliable process for safe treatment of halogenated antibiotic containing wastewater.

Cu(i) catalysis for selective condensation/bicycloaromatization of two different arylalkynes: direct and general construction of functionalized C-N axial biaryl compounds.

Selective condensation/bicycloaromatization of two different arylalkynes is firstly developed under ligand-free copper(i)-catalysis, which allows the direct synthesis of C-N axial biaryl compounds in high yields with excellent selectivity and functional group tolerance. Due to the critical effects of Cu(i) catalyst and HFIP, many easily occurring undesired reactions are suppressed, and the coupled five-six aromatic rings are constructed via the selective formation of two C(sp2)-N(sp2) bonds and four C(sp2)-C(sp2) bonds. The achievement of moderate enantioselectivity verifies its potential for the simplest asymmetric synthesis of atropoisomeric biaryls. Western blotting demonstrated that the newly developed compounds are promising targets in biology and pharmaceuticals. This unique reaction can construct structurally diverse C-N axial biaryl compounds that have never been reported by other methods, and might be extended to various applications in materials, chemistry, biology, and pharmaceuticals.

Embedding few-layer Ti3C2Tx into alkalized g-C3N4 nanosheets for efficient photocatalytic degradation.

Solution of the increasingly important problem of aquatic pollution requires the use of an economical, energy-efficient, highly effective and environmentally-friendly catalyst. Polymeric carbon nitride (C3N4) has shown to be a promising metal-free photocatalyst that however suffers from strong charge recombination and poor conductivity, while MXenes have shown to be perfect co-catalysts for the photocatalytic process but show poor stability. In this study, we successfully constructed a robust heterostructure photocatalyst in which few-layer Ti3C2Tx was embedded into alkalized C3N4 without being oxidized. The photocatalyst showed stable and effective photocatalytic performance for the removal of tetracycline hydrochloride and other organic compounds under visible light irradiation. Different characterization methods were used to elucidate the morphology and structure of the as-prepared photocatalyst. The robust heterostructure and the intimate interaction between the two constituents of the composite were verified. Based on the van der Waals heterostructure, Ti3C2Tx acts as the electron acceptor and helps to form Schottky junction, preventing charge recombination of the photocatalyst. And in the meantime, the electrons from C3N4 protect Ti3C2Tx from oxidation. SEM and XRD results demonstrated that the Ti3C2Tx structure remains unchanged after calcination and after photodegradation experiments. Furthermore, a possible mechanism for photocatalytic tetracycline hydrochloride degradation was proposed based on the results of radical scavenging experiments. This work provides a strategy to strengthen heterostructure between 2D materials, and shows that carbon nitride and Mxenes could be promising materials for photocatalytic wastewater pre-treatment applications.

Static and continuous flow photoelectrocatalytic treatment of antibiotic wastewater over mesh of TiO2 nanotubes implanted with g-C3N4 nanosheets.

Photoelectrocatalytic (PEC) especially continuous flow PEC process for organic wastewater treatment greatly depends on both catalytic capacity and practical availability of electrode materials. In this study, g-C3N4 nanosheets are implanted into TiO2 nanotube arrays mesh (TCNs) through direct calcination of TiO2 nanotube array mesh loading melamine precursor. The TCNs photoelectrodes exhibit excellent PEC activity in organic pollutant degradation. Typically, almost 100% of tetracycline (TC, an emerging refractory antibiotic pollutant) is removed in 2 h and TOC removal reaches to 93% in 3 h under simulated solar irradiation at 1 V vs. Ag/AgCl. Theoretical calculations are performed to predict the primary reactive sites for radical species attack and the intermediates are identified. Meanwhile, the ecotoxicity of TC-containing wastewater greatly decrease after PEC treatment. Impressively, because of the mesh screen effect and high catalytic capacity of the photoelectrode, continuous flow PEC process keeps 80% removal efficiency of TC in real wastewater in the absence of additional background electrolyte. After prolonging 20 h, the level of treatment is highly stable. This work would set an example for potential large-scale treatment of organic wastewater using PEC process.

Assessment of the periodontal health status in patients undergoing orthodontic treatment with fixed appliances and Invisalign system: A meta-analysis.

BACKGROUND: At present, many scholars have studied the periodontal health status of patients undergoing orthodontic treatment with fixed appliances and invisalign. However, those results are inconsistent. Therefore, we conducted this meta-analysis, and then provide reference for clinical treatment. METHODS: Most databases, such as the Cochrane Library, EMBASE, PubMed, Medline, Chinese Biomedical Literature Database, CNKI, and Wan Fang Data were retrieved for related articles from the establishment of the database to October 2017. Meanwhile, we also searched the references of the related literatures manually, in order to increase the included literatures. Two researchers screened the related literatures according to the inclusion criteria and exclusion criteria. Stata 12.0 software was used for data analysis, and results are estimated by odds ratio (OR) and 95% confidence interval (CI). RESULTS: Finally, 7 articles, including 368 patients, were included into our meta-analysis. Meta-analysis results showed that there was no statistically significant difference of gingival index (GI) and sulcus probing depth (SPD) status between the invisalign group and the control group, including at 1, 3, and 6 months (all P > .05). When compared with the control group, the invisalign group presented a lower plaque index (PLI) and sulcus bleeding index (SBI) status at 1 month (OR = -0.53, 95% CI: -0.89 to -0.18; OR = -0.44, 95% CI: -0.70 to -0.19, respectively), 3 months (OR = -0.69, 95% CI: -1.12 to -0.27; OR = -0.49, 95% CI: -0.93 to -0.05, respectively), and 6 months (OR = -0.91, 95% CI: -1.47 to -0.35; OR = -0.40, 95% CI: -0.63 to -0.07, respectively). Subgroup analysis showed that the SPD status was lower in the invisalign group at 6 months when measured the teeth using Ramfjord index (OR = -0.74, 95% CI: -1.35 to -0.12). However, there was no statistically significant difference between the 2 groups when using other measure methods (OR = 0.12, 95% CI: -0.26 to 0.17). CONCLUSION: Our meta-analysis suggests that comparing with the traditional fixed appliances, patients treated with invisalign have a better periodontal health. However, more studies are needed to confirm this conclusion in the future.

Application of enzyme-hydrolyzed cassava dregs as a carbon source in aquaculture.

As a kind of tropical agricultural solid waste, cassava dregs had become a thorny nonpoint source pollution problem. This study investigated the feasibility of applying cassava dregs as a substitute for sucrose in biofloc technology (BFT) systems. Three types of biofloc systems (using three different carbon sources sucrose (BFT1), cassava dregs (BFT2) and enzyme-hydrolyzed cassava dregs (BFT3) respectively), and the control were constructed in this experiment in 200L tanks with a C/N ratio of 20/1. The comparison of the water quality indicators (The total ammonia nitrogen (TAN), nitrite (NO2--N), nitrate (NO3--N), chemical oxygen demand (COD)), biofloc for the above four groups was performed, and the results indicated that BFT3 showed greater potential to the formation of biofloc, which was beneficial for the water quality control. So the shrimp survival rate was the highest and the feed conversion rate was the lowest in BFT3. Besides, the high-throughput sequencing results showed that the relative abundance of heterotrophic bacteria in the top 30 dominant microbial communities in BFT3 was higher than those in BFT1 and BFT2 by 20.70% and 1.19%, respectively, which could decrease TAN to improve the water quality. Overall, the results had proved that the cassava dregs of enzymes hydrolysis could be used as an ideal and cheap carbon source in BFT.

[Operation of chronic sphenoid sinusitis with endoscopic sinus surgery].

OBJECTIVE: To evaluate the method and treatment effect of endoscopic sinus surgery for chronic sphenoid sinusitis. METHOD: Fifty cases, 84 sides of chronic sphenoid sinusitis patients were treated with endoscopic sinus surgery. RESULT: In the follow-up of 6-12 months, 61 sides (72.62%) were cured; 13 sides (15.48%) were mended; 10 sides (11.90%) were ineffective; 74 sides were effective, the effectiveness rate were 88.10%. CONCLUSION: Treatment with endoscopic sinus surgery is a safe, effective method with little pain for chronic sphenoid sinusitis.